Background: Local tumor failure remains a major problem after radiation-based nonsurgical treatment for unresectable locally advanced Non-Small Cell Lung Cancer (NSCLC)and inoperable stage II NSCLC .The aim of this study was to evaluate the feasibility of Simultaneous Integrated Boos of intensity modulated radiation therapy (SIB-IMRT) to Stage II-III NSCLC with metastatic lymph nodes. Methods: Patients were diagnosed by pathology or PET-CT. PTV was divide into two parts as follow, the PTV of primary tumor (PTVp) and the PTV of metastatic lymph nodes (PTVn) .The radiation doses were simultaneously prescripted 78Gy (BED = 101.48Gy) for PTVp and 60-65Gy (BED = 73.6-81.25Gy) for PTVn, 26f/ 5.2 weeks .Response was scored according to WHO criteria. Radiotherapy toxicity was scored according to RTOG criteria .Hematology and gastrointestinal toxicity were scored according to CTCAE1.0 criteria. Results: A total of 20 patients were enrolled. 17 patients were diagnosed by pathology and 3 patients were diagnosed by PET-CT . All patients were treated with SIB-IMRT. The objective response rate (ORR) was 90%, with CR 25%, PR 65%, NC 10% and PD 0%. Although Radiation toxicitiy was common, there were no grade≥3,with Radiation pneumonitis (10 cases), esophagitis (17 cases) and dermatitis (12 cases). The local control rates at 1, 3 and 5 years were 85%, 75% and 70%, respectively. The overall survival(OS)and local progression-free survival(LPFS) rates at 1, 3 and 5 years were 90%, 42.6%, 35.5% and 84.4%, 35.5% , 28.4%, respectively. The MST was 24 months. Conclusions: SIB-IMRT can significantly improve ORR and suivival for stage II-III NSCLC with metastatic lymph nodes , with high safety and satisfactory efficacy . Keywords: cancer/non-small-cell lung cancer; radiation therapy /SIB-IMRT; efficacy; safety Retrospective Trial Registration: (ChiCTR 2000029304)